Ash dieback
Ash dieback is a fungal disease that prevents ash trees from taking up water and minerals from their roots, causing leaf loss, dying branches and ultimately death. Infected trees become progressively fragile, often succumbing to secondary infections which have the ability to effect stability.
It is estimated that the disease will kill up to 90% of all ash trees in the UK, over the next decade. There is currently no cure or method of control to prevent or protect against it, which means trees that have succumbed to ash dieback must be felled. Some ash trees on Horsham District Council land have already been killed by the disease and have been felled in the past couple of years.
What ash dieback looks like
Ash trees that have become infected may display a range of symptoms but most obvious are dead twigs or branches with no leaves in the summer (June to September). The disease weakens the tree over time, with the canopy becoming thinner and thinner.
In this aerial shot of Horsham District Council land, the dying ash trees are clearly identifiable.
How we are tackling ash dieback on Horsham District Council land
There are thousands of ash trees on Horsham District Council land, both within woodland and parks and open spaces. More and more of these trees are showing the symptoms of ash dieback and the Council is working on a plan of action for the worst affected sites.
From this winter, and for the next few years, we will be removing diseased and dying ash from many of our sites, including Warnham Local Nature Reserve and Southwater Country Park. This will be a phased approach, targeting woods in order of the urgency of the work.
Some of our woods are between 30-50% ash, so their removal will have a significant impact on the landscape, but this is unavoidable.
How we decide when to fell an infected tree
It is inevitable that we will need to fell infected trees on Council land that may cause harm to users of our sites, or to neighbouring property. We monitor trees on our land on a regular basis, with the interval between inspections dependent on the site location and history. We are trailing aerial survey using a drone, to inspect the canopy of seriously affected woodland areas from overhead.
We can track the progress of ash dieback in an individual tree by the loss of the canopy and amount of dead wood visible. We want to retain ash trees for as long as possible to see if they have natural resistance. However, once approximately 40% or more of the canopy has been lost, the tree is succumbing to ash dieback and will need to be felled. In some cases it will be necessary to fell a small number of healthy trees as part of the overall process to allow access into a wood, or to ensure dangerous trees can be felled safely. In some cases the trees will be left where they fall, in others the timber may be removed – it will depend on a site-by site basis.
Before we start work
Before we start felling works in a block of woodland we need to obtain a felling licence from the Forestry Commission, unless the trees are already dead or presenting a risk to persons or property.
Where a significant amount of felling is due to take place, we will contact residents who neighbour the land and provide more detailed plans for that site. Information notices will be put on-site, and we will update this webpage with as much information as possible. Please be aware, we will not be able to do this if we fell a single tree or a small clump.
Timescales and locations
We expect to be dealing with ash dieback for the next five years or so, as more trees become infected. We intend that most of the woodland felling should take place in the winters, but trees may be felled at any time during the year, if we believe there is a risk to public safety.
Work will start this winter 2021-22 with an area of woodland in North Horsham. Other areas with significant amounts of ash include Warnham Nature Reserve and Southwater Country Park.
Further information on ash dieback
In the majority of cases we will be relying on the process of natural regeneration to allow a wooded area to repair itself. This means saplings arising from the seedbank within the woodland’s soil. Some ash stumps may resprout, but this means that they were not entirely dead, rather than they were healthy and were felled by mistake.
Trees developing from natural regeneration are perfectly suited to their growing environment, establishing far more quickly and more successfully than larger trees which must be planted in and take some years to grow new roots and establish themselves properly. If there is a notable specimen ash tree in an open setting, we may consider replanting with another tree, but of a different species, not ash.
We will not be able to provide screening.
There are currently no treatments or methods of control. Up to 10% of ash trees are thought to have some natural immunity, but with only 1-2% being highly resistant to the disease. Once a tree starts showing signs of infection, the progression of the disease depends on the health of the individual tree, whether it suffers from other stresses, such as drought or pollution. This takes 2-4 years, on average, between the first visible signs of infection and a tree needing to be felled before it becomes unsafe.
As a general rule, large, mature trees seem to be able to survive for longer than younger trees, and trees in a rural woodland, with good growing conditions may have greater resilience than urban trees.
The microscopic spores of the fungus are carried for miles by the wind and infect the tree through its leaves.
We have a statutory duty of care to the public to maintain trees to ensure their safety. Whilst it will be upsetting to see any tree felled, let alone an area of woodland, we have no other choice but to carry out these operations.
Inevitably the loss of ash from our woodlands will impact on wildlife through loss of habitat and food. We will only be taking out ash that are definitely dying and minimise the impact to the wider woodland. Where safe to do so we will leave trunks to create standing dead wood habitat.
Ash dieback control in Benns Field, Southwater
Ash dieback work is due to begin at Benns Field, Southwater week commencing Monday 6 February, as highlighted on the map (subject to weather conditions).
This work is indented to exclusively address the effects of Ash dieback Disease – no other tree species will be removed.
This work is expected to last approximately one week.
Whilst the work is on-going it may be necessary to restrict access to the woodland for Health and Safety Reasons.
Please follow all on-site signage and instruction during this time.
Ash dieback control in Walnut Tree Plantation, Warnham Local Nature Reserve
Ash dieback control work will take place in Walnut Tree Plantation, Warnham Local Nature Reserve.
This work is due to start w/c 3 January 2023 and expected to last six weeks.
The highlighted area on the map indicates where ash dieback control work will take place.
Please be aware if you are visiting the Reserve there will be no access to Walnut Tree Plantation and there may be additional noise and disruption from the work.
Please follow all on-site signage.
The frequently asked questions detailed below are specific to this location.
No, initially only those trees which are either dead or displaying the symptoms of Ash dieback will be removed. However, additional trees which have grown in close proximity to their neighbours and benefited from the mutual protection provided from high winds etc may require removal also.
Such trees are often unable to adapt sufficiently swiftly to the environmental changes and are at risk of failing. Wherever practicable the aim is to retain healthy trees that do not present a risk to the reserve’s staff or users.
Given the extent of the proposed works a Felling Licence has been issued to Horsham District Council by the Forestry Commission. The highlighted areas do not form part of an Ancient Woodland, the trees are not subject to the protection of Tree Preservation Orders (TPOs) or growing within a designated Conservation Area (CA).
All work will take place outside of the bird nesting season – 1st March until 31st July.
However, it is acknowledged that there can be extensions at both ends of this period. For this reason, tree removal will not start until the autumn.
The Council’s Countryside & Ecology Manager will undertake the appropriate surveys to establish the presence of any further protected species. Where required amendments to the works method statements will be made to mitigate any disturbance.
While essential it is acknowledged that the initial tree removal may be disruptive, however, it will also provide opportunities for positive change.
- Where appropriate high stumps will be retained (c. 2m) the combination of a connected above & below ground woody structure is especially beneficial to stag beetles.
- The retention taller stumps (monoliths) will encourage the presence of aerial fungi, invertebrates and vertebrates.
- Increased light levels should encourage the re-establishment of woodland floor plants.
- The following tree planting and natural regeneration will provide a more diverse and robust tree population.
The plantation will be split into two separate compartments (as shown on the image above).
Compartment 1.
Areas cleared of trees will be re-planted with a mixture of native high canopy trees and understory plants. It is hoped that the introduction of a more diverse species selection will enhance current biodiversity and provide a more robust response to disease in the future.
Compartment 2.
In this area we will trialling the natural regeneration method, allowing the compartment to be recolonised by species naturally occurring within the existing seedbank. Scientific evidence shows that the UK’s native tree species have a wide genetic diversity, this diversity combined with local provenance should allow accelerated & successful establishment.
No, accessing the woodland to remove the felled trees has the potential to cause damage to field layer plants, soil structure and would be cost prohibitive. Tree canopies will be chipped back onto the woodland floor. Over a relatively short period of time this material will be incorporated back into the soil, improving its nutritional properties and structure.
Material that cannot be chipped will be cut into uniform lengths and stacked neatly to create habitat piles. Such structures provide multiple opportunities to further enhance and increase biodiversity.
Ash dieback control in Bartholomew Way (North)
Ash dieback work in Bartholomew Way, North is due to begin w/c 3 January 2023 (weather permitting).
The attached map shows the area where work will be undertaken.
In the area shown in green, all affected or dead ash trees will be removed.
In addition, in the area shown in orange, it is proposed to create an area clear of trees between the boundary fences and the woodland edge.
The depth of this area will be dependent on current tree cover but will range from between 1m and 4m (maximum). In many instances this may just require the removal of just 1 or 2 trees on the end of each row.
This action will remove encroachment of boundaries, increase light levels within properties and limit the potential for tree related damage.
This work is expected to last approximately six weeks.
Whilst the work is on-going it may be necessary to restrict access to the woodland for Health and Safety Reasons.
Please follow all on-site signage and instruction during this time.
Ash dieback control in Rascals Close, Southwater
Ash dieback work is due to begin within the land east of 3 and 5 Rascals Close during December as highlighted on the map (subject to weather conditions).
This work is expected to last approximately one week (avoiding the Christmas period).
Whilst the work is on-going it may be necessary to restrict access to the woodland for Health and Safety Reasons.
Please follow all on-site signage and instruction during this time.
Completed Ash dieback works
Ash dieback control work has already taken place in Bartholomew Way, Horsham ( January 2022). The highlighted area on the map indicates where Ash dieback control work too place take place.
Additional work took place in Granary Way, Horsham (February 2022.)
The highlighted map indicates where ash dieback control work took place.
